1. Technical Field
This invention relates to alarm systems and, more particularly, to a dual intercom-camera-interfaced smoke/fire detection system and associated method for notifying multiple persons of an emergency event.
2. Prior Art
Various systems are known for the detection of alarm conditions. One particular form of such a system is a smoke or fire detecting system. Upon receipt of inputs from one or more of the detectors of the system, a control unit associated with the system is able to make a determination as to whether or not a fire condition is present in one or more regions of interest. A variety of techniques have been used in the past for the purpose of making this determination. Sensors of smoke such as photoelectric smoke detectors or ionization-type smoke detectors are intended to provide outputs indicative of sensed levels of ambient smoke. Environmental noise, such as dust particles or insects which may enter the respective detector can produce variations in output signals from the sensors which are not in any way correlated with the presence of smoke. These noise outputs can produce false alarms if the sensitivity of the respective detector is high enough. Such false alarms are undesirable. Based on the above mentioned history, it would be advantageous to provide an alarm system and method that detected both smoke and fire while minimizing false alarms with the ability to communicate the alarm through an existing intercom system.
This prior art example shows an alarm system which incorporates a plurality of highly sensitive, early warning, smoke detectors for distinguishing between detector signals in response to ambient smoke and detector signals in response to the presence of non-smoke materials. Such detectors are spatially arranged in predetermined regions. Information concerning the arrangement of the detectors is stored in the common control unit. Additionally, a performance history for each of the detectors is also stored in the control unit.
If one of the detectors exhibits a relatively large output which is large enough to indicate a possible fire, a previously stored history from the outputs of that detector is analyzed. If the previously stored history indicates a fire related profile, such as a relatively gradual increase in smoke level over a period of time, the signal from that detector is regarded as being indicative of smoke and an alarm is indicated. If the signal from the detector shows a relatively fast increase, from a very low level to an alarm level in a short period of time, fibrous material may have entered the detector. The output from at least one other detector in the same region is analyzed. If the second detector confirms the presence of smoke, the first detector is regarded as indicating an alarm condition. If the second detector does not indicate the presence of smoke, even a very low level of smoke, the output from the first detector is regarded as being due to a non-smoke condition, such as an intrusive fibrous material. Unfortunately, this prior art example does not communicate the alarm signal throughout an intercom system.
Another prior art example shows an expandable and modular intercom and annunciation system that includes a plurality of signal sources such as smoke detectors, breakage detectors, intrusion detectors, telecommunication detectors (such as ringers), and gas detectors.
The intercom unit has a processor, a memory, and a user interface including an audio output. The processor of the intercom unit is programmed with instructions to determine relative priorities among the plurality of common communication protocol signals, to select a first common communication protocol signal having a highest relative priority during a selected time interval, to announce a message corresponding to the first common communication protocol signal during the selected time interval, and to maintain a quiet interval for an announcement entered by an individual via the user interface. Unfortunately, this prior art example is not designed to communicate the alarm signals through an intercom system.
Another prior art example shows an integrated telephone, intercom, security and control system for a building having a plurality of units that utilizes a plurality of telephone lines located throughout the building which are connected at one end to telecommunications equipment located in the units and throughout common areas of the building. A digital switching device is connected to the other end each of the telephone lines and arranged to connect at least one of the telephone lines to at least one of another of the telephone lines or to an outside telephone line at the option of a user of the telecommunications equipment. A plurality of sensors located in the units and throughout common areas of the building is arranged for generating signals in response to conditions therein, which are then transmitted to a plurality of control modules connected to the digital switching device by at least one of the telephone lines. The control modules are further adapted to send information to a central monitoring station via the telephone lines indicative of the respective conditions and the central monitoring station is adapted to at least receive and store this information in its memory and output data indicative of the respective conditions. Unfortunately, this prior art example requires the use of telephone lines connected throughout the building.